The present invention relates to conical centrifugal baskets especially for continuously operating centrifuges, particularly suitable for the centrifuging required in the production of sugar. Such centrifugal baskets are equipped with separation screens arranged inside the basket. The screens may be provided in several segments.
Continuously operating centrifuges equipped with a conical centrifugal basket are receiving an ever increasing acceptance in practice, especially in the sugar industry. The proper function of such centrifuges depends, among other factors, on the proper adaptation or adjustment of several factors relative to each other. Thus, the sliding characteristics of the material to be treated and the sliding characteristics of the screening surface as well as the slope or inclination of the centrifugal basket, that is its cone angle, must be balanced exactly relative to each other. If such balancing is not assured, the material to be centrifuged either is not transported through the centrifugal basket, or rather along its screen or the material follows the axially directed component of the centrifugal force, whereby the material is discharged from the centrifugal basket at a much too high rate.
Since the sliding characteristics of the material passing through the centrifugal basket may vary considerably due to the removal of the liquid phase inside the centrifuge, it is necessary to construct the centrifugal baskets in such a manner that they comprise zones of different cone angles or different slopes. In prior art centrifugal baskets of this type it was customary heretofore to use either a single piece screen or a single piece screen for each segment in the axial direction, whereby the screen was bent in a varying manner in accordance with the varying cone angle or slope. It has also been customary to use for each differently sloped basket section a screen or screen segment which was secured to the basket section by conventional clamping rings at the location of the narrowest diameter of the respective cone section.
In connection with further developements of continuously operating sugar centrifuges it has become necessary to an ever increasing extent to condition the massecuite directly in the centrifuge. Stated differently, it has become necessary to prepare the massecuite in a certain manner for the subsequent separation job. For such preparation it is necessary to provide for certain residence times or durations in predetermined zones of the centrifugal basket. Such residence times are determined by respectively steep basket slopes which, in the extreme may involve basket sections of cylindrical shape.
It has been found that securing the screens in this type of centrifuge in the conventional manner by using clamping rings in each individual section or stage, a relatively complicated screen securing would result. In addition, one would have to take into account especially certain radial, abrupt diameter increases corresponding to the width of the clamping rings. In addition, the useful axial height of the centrifugal basket would be diminished in accordance with the axial height of the clamping rings.